The Santa Cruz Go Association is an AGA associated Go Club that meets in downtown Santa Cruz on Thursday evenings. The place is Cafe Pergolesi, from 7:30 until 10:30.
The UC Santa Cruz Go Club is now defunct, but some of its members play at Cafe Pergolesi. If you see the wiki pages for the UCSC Go Club, realize that they are a bit out of date, but that going to Pergolesi is still the way to find a game in Santa Cruz.